The major aim of the project is to elucidate further the role of working memory in the acquisition of reading skill. In Phase I, three groups of elementary school students were recruited. Two groups (N=40 in each) are poor readers; one group meets criteria for developmental reading disability and the other group is slow learners. Forty normal for age readers with Attention Deficit Disorder (ADD) serve as a comparison group. While all groups exhibit impairments in working memory, the pattern of sub-component deficits is expected to vary. Especially at issue is why approximately half of ADD children learn to read and spell at an age-appropriate rate despite working memory dysfunctions (e.g., below normal digit span scores on the WISC-R). Subjects are compared on a wide variety of tasks that assess reading skill and that tap different components and/or correlates of working memory (e.g., articulation rate, confrontational naming rate, serial memory span). Each of the latter tasks are done under two or more conditions to explore the role of stimulus type and distractors on working memory. Electrophysiological monitoring is done during two tasks, allowing assessment of (1) event related potentials to rhyming and non-rhyming word and nonsense word pairs and (2) EEG coherence during mental arithmetic and viewing of word and letter strings. It is expected that slower articulation rates and impaired phonological sensitivity will underlie working memory dysfunctions in the dyslexic and the slow learner groups. The working memory deficits of the ADD only group will be hypothesized to be innate (limited capacity) or strategic and not motivational in origin if incentive conditions do not improve their performance. In Phase II, it is proposed to recruit 40 adolescent dyslexics (aged 12 to 16) to compare with the three groups studied in Phase I. This older dyslexic group will be an approximate reading age match for the younger ADD normal readers, but are predicted to differ on working memory subprocesses and phonological skills.